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Date: Tue, 20 Feb 2024 17:57:16 -0800
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: kill heap-based allocation
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References: <20240207164620.1536038-1-jaegeuk@kernel.org>
 <ZdUQ6uKYyfzn5Fhv@google.com>
 <1a9d9c59-dbba-4d9e-8804-2fb92c56b5b3@kernel.org>
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On 02/21, Chao Yu wrote:
> On 2024/2/21 4:51, Jaegeuk Kim wrote:
> > No one uses this feature. Let's kill it.
> > 
> > Reviewed-by: Daeho Jeong <daehojeong@google.com>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> > 
> >   Change log from v1:
> >    - keep mount options but give warnings instead
> > 
> >   Documentation/filesystems/f2fs.rst |  4 +--
> >   fs/f2fs/gc.c                       |  5 ++-
> >   fs/f2fs/segment.c                  | 54 ++++--------------------------
> >   fs/f2fs/segment.h                  | 10 ------
> >   fs/f2fs/super.c                    |  9 +----
> >   5 files changed, 11 insertions(+), 71 deletions(-)
> > 
> > diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> > index 9ac5083dae8e..c30a800604fd 100644
> > --- a/Documentation/filesystems/f2fs.rst
> > +++ b/Documentation/filesystems/f2fs.rst
> > @@ -126,9 +126,7 @@ norecovery		 Disable the roll-forward recovery routine, mounted read-
> >   discard/nodiscard	 Enable/disable real-time discard in f2fs, if discard is
> >   			 enabled, f2fs will issue discard/TRIM commands when a
> >   			 segment is cleaned.
> > -no_heap			 Disable heap-style segment allocation which finds free
> > -			 segments for data from the beginning of main area, while
> > -			 for node from the end of main area.
> > +no_heap			 Deprecated.
> 
> heap/no_heap			Deprecated
> 
> Otherwise, it looks good to me.
> 
> Reviewed-by: Chao Yu <chao@kernel.org>
> 
> BTW, do we need to kill heap-based allocation in mkfs.f2fs as well?

I was about to work on it after kernel change tho. Can you write one? :)

> 
> Thanks,
> 
> >   nouser_xattr		 Disable Extended User Attributes. Note: xattr is enabled
> >   			 by default if CONFIG_F2FS_FS_XATTR is selected.
> >   noacl			 Disable POSIX Access Control List. Note: acl is enabled
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index 501b93b45b6c..a089a938355b 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -280,12 +280,11 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> >   			p->max_search > sbi->max_victim_search)
> >   		p->max_search = sbi->max_victim_search;
> > -	/* let's select beginning hot/small space first in no_heap mode*/
> > +	/* let's select beginning hot/small space first. */
> >   	if (f2fs_need_rand_seg(sbi))
> >   		p->offset = get_random_u32_below(MAIN_SECS(sbi) *
> >   						SEGS_PER_SEC(sbi));
> > -	else if (test_opt(sbi, NOHEAP) &&
> > -		(type == CURSEG_HOT_DATA || IS_NODESEG(type)))
> > +	else if (type == CURSEG_HOT_DATA || IS_NODESEG(type))
> >   		p->offset = 0;
> >   	else
> >   		p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 94c4f7b16c19..09af17af4e7a 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -2634,16 +2634,14 @@ static int is_next_segment_free(struct f2fs_sb_info *sbi,
> >    * This function should be returned with success, otherwise BUG
> >    */
> >   static void get_new_segment(struct f2fs_sb_info *sbi,
> > -			unsigned int *newseg, bool new_sec, int dir)
> > +			unsigned int *newseg, bool new_sec)
> >   {
> >   	struct free_segmap_info *free_i = FREE_I(sbi);
> >   	unsigned int segno, secno, zoneno;
> >   	unsigned int total_zones = MAIN_SECS(sbi) / sbi->secs_per_zone;
> >   	unsigned int hint = GET_SEC_FROM_SEG(sbi, *newseg);
> >   	unsigned int old_zoneno = GET_ZONE_FROM_SEG(sbi, *newseg);
> > -	unsigned int left_start = hint;
> >   	bool init = true;
> > -	int go_left = 0;
> >   	int i;
> >   	spin_lock(&free_i->segmap_lock);
> > @@ -2657,30 +2655,10 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> >   find_other_zone:
> >   	secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> >   	if (secno >= MAIN_SECS(sbi)) {
> > -		if (dir == ALLOC_RIGHT) {
> > -			secno = find_first_zero_bit(free_i->free_secmap,
> > +		secno = find_first_zero_bit(free_i->free_secmap,
> >   							MAIN_SECS(sbi));
> > -			f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
> > -		} else {
> > -			go_left = 1;
> > -			left_start = hint - 1;
> > -		}
> > -	}
> > -	if (go_left == 0)
> > -		goto skip_left;
> > -
> > -	while (test_bit(left_start, free_i->free_secmap)) {
> > -		if (left_start > 0) {
> > -			left_start--;
> > -			continue;
> > -		}
> > -		left_start = find_first_zero_bit(free_i->free_secmap,
> > -							MAIN_SECS(sbi));
> > -		f2fs_bug_on(sbi, left_start >= MAIN_SECS(sbi));
> > -		break;
> > +		f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
> >   	}
> > -	secno = left_start;
> > -skip_left:
> >   	segno = GET_SEG_FROM_SEC(sbi, secno);
> >   	zoneno = GET_ZONE_FROM_SEC(sbi, secno);
> > @@ -2691,21 +2669,13 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> >   		goto got_it;
> >   	if (zoneno == old_zoneno)
> >   		goto got_it;
> > -	if (dir == ALLOC_LEFT) {
> > -		if (!go_left && zoneno + 1 >= total_zones)
> > -			goto got_it;
> > -		if (go_left && zoneno == 0)
> > -			goto got_it;
> > -	}
> >   	for (i = 0; i < NR_CURSEG_TYPE; i++)
> >   		if (CURSEG_I(sbi, i)->zone == zoneno)
> >   			break;
> >   	if (i < NR_CURSEG_TYPE) {
> >   		/* zone is in user, try another */
> > -		if (go_left)
> > -			hint = zoneno * sbi->secs_per_zone - 1;
> > -		else if (zoneno + 1 >= total_zones)
> > +		if (zoneno + 1 >= total_zones)
> >   			hint = 0;
> >   		else
> >   			hint = (zoneno + 1) * sbi->secs_per_zone;
> > @@ -2763,8 +2733,7 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)
> >   	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> >   		return 0;
> > -	if (test_opt(sbi, NOHEAP) &&
> > -		(seg_type == CURSEG_HOT_DATA || IS_NODESEG(seg_type)))
> > +	if (seg_type == CURSEG_HOT_DATA || IS_NODESEG(seg_type))
> >   		return 0;
> >   	if (SIT_I(sbi)->last_victim[ALLOC_NEXT])
> > @@ -2784,21 +2753,12 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)
> >   static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
> >   {
> >   	struct curseg_info *curseg = CURSEG_I(sbi, type);
> > -	unsigned short seg_type = curseg->seg_type;
> >   	unsigned int segno = curseg->segno;
> > -	int dir = ALLOC_LEFT;
> >   	if (curseg->inited)
> > -		write_sum_page(sbi, curseg->sum_blk,
> > -				GET_SUM_BLOCK(sbi, segno));
> > -	if (seg_type == CURSEG_WARM_DATA || seg_type == CURSEG_COLD_DATA)
> > -		dir = ALLOC_RIGHT;
> > -
> > -	if (test_opt(sbi, NOHEAP))
> > -		dir = ALLOC_RIGHT;
> > -
> > +		write_sum_page(sbi, curseg->sum_blk, GET_SUM_BLOCK(sbi, segno));
> >   	segno = __get_next_segno(sbi, type);
> > -	get_new_segment(sbi, &segno, new_sec, dir);
> > +	get_new_segment(sbi, &segno, new_sec);
> >   	curseg->next_segno = segno;
> >   	reset_curseg(sbi, type, 1);
> >   	curseg->alloc_type = LFS;
> > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> > index 6fadfb634aac..0f1a5210c163 100644
> > --- a/fs/f2fs/segment.h
> > +++ b/fs/f2fs/segment.h
> > @@ -131,16 +131,6 @@ static inline void sanity_check_seg_type(struct f2fs_sb_info *sbi,
> >   #define SECTOR_TO_BLOCK(sectors)					\
> >   	((sectors) >> F2FS_LOG_SECTORS_PER_BLOCK)
> > -/*
> > - * indicate a block allocation direction: RIGHT and LEFT.
> > - * RIGHT means allocating new sections towards the end of volume.
> > - * LEFT means the opposite direction.
> > - */
> > -enum {
> > -	ALLOC_RIGHT = 0,
> > -	ALLOC_LEFT
> > -};
> > -
> >   /*
> >    * In the victim_sel_policy->alloc_mode, there are three block allocation modes.
> >    * LFS writes data sequentially with cleaning operations.
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index 5aaf44c4698b..916e82e9c307 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -733,10 +733,8 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> >   			clear_opt(sbi, DISCARD);
> >   			break;
> >   		case Opt_noheap:
> > -			set_opt(sbi, NOHEAP);
> > -			break;
> >   		case Opt_heap:
> > -			clear_opt(sbi, NOHEAP);
> > +			f2fs_warn(sbi, "heap/no_heap options were deprecated");
> >   			break;
> >   #ifdef CONFIG_F2FS_FS_XATTR
> >   		case Opt_user_xattr:
> > @@ -1962,10 +1960,6 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> >   	} else {
> >   		seq_puts(seq, ",nodiscard");
> >   	}
> > -	if (test_opt(sbi, NOHEAP))
> > -		seq_puts(seq, ",no_heap");
> > -	else
> > -		seq_puts(seq, ",heap");
> >   #ifdef CONFIG_F2FS_FS_XATTR
> >   	if (test_opt(sbi, XATTR_USER))
> >   		seq_puts(seq, ",user_xattr");
> > @@ -2142,7 +2136,6 @@ static void default_options(struct f2fs_sb_info *sbi, bool remount)
> >   	set_opt(sbi, INLINE_XATTR);
> >   	set_opt(sbi, INLINE_DATA);
> >   	set_opt(sbi, INLINE_DENTRY);
> > -	set_opt(sbi, NOHEAP);
> >   	set_opt(sbi, MERGE_CHECKPOINT);
> >   	F2FS_OPTION(sbi).unusable_cap = 0;
> >   	sbi->sb->s_flags |= SB_LAZYTIME;